The transition to low speed vehicles for intra-city travel
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A transition to low speed vehicles (LSVs), a federally-designated class of vehicles smaller, lighter and slower (limited to maximum speeds between 20 and 25 mph) than conventional automobiles, for intra-city travel offers several advantages. Their smaller size provides roadway space for other modes such as cycling and reduces the amount of land dedicated to vehicles. Their lower maximum speeds are more compatible with operation in populated areas where cars traveling at 30 mph prove deadly for pedestrians and people biking, and their energy usage and emissions are less than conventional automobiles. Communities such as Lincoln, CA, Peachtree City, GA, and those in the South Bay Cities and Western Riverside Councils of Governments in California recognize the benefits of using LSVs and actively provide infrastructure and programs to support their use. Considering the advantages of LSVs, this dissertation demonstrates potential ways to transition to LSVs and seeks to answer a question considered key to their adoption as the means of motorized travel in the city: Could LSVs also offer a travel time advantage? The basis for this seemingly paradoxical question is the observation that because of their smaller size, lower weight, and slower speed, more space- and operationally-efficient intersections, such as LSV-scaled roundabouts, overpasses and interchanges, are possible within the existing right-of-way to replace signalized intersections. The hypothesis that LSVs can offer comparable or better travel time compared to conventional automobiles assumes the removal of intersection delay will allow LSVs to make-up for their slower speeds. The methodology to test the hypothesis uses dynamic traffic assignment to compare average system, corridor and origin to destination travel times for conventional automobiles and LSVs in a subnetwork of Austin, Texas during transition periods when both vehicles are permitted and when only LSVs may be used for intra-city motorized travel. The findings indicate LSVs can offer similar and in some cases better average travel times than those for conventional automobiles, especially for the LSV-only network. However, careful planning is required during the transition stages when both vehicle types are in operation to maintain acceptable travel times for both conventional automobiles and LSVs.